1. Field of the Invention
The present invention relates a method of determining efficient parameters in chemical-mechanical polishing, wherein the method is based on imitating a virtual CMP process in neural network progress and then determining a parameter set inputted into an electronic polishing machine to make wafer polishing efficient.
2. Description of Related Art
A chemical-mechanical polishing (CMP) is a process used to manufacture semiconductor wafers. Typically, the chemical-mechanical polishing involves rotating a thin, flat semiconductor wafer against a polishing pad, rotating the polishing pad against the wafer, or both. A chemical slurry containing a polishing agent such as alumina or silica, acts as an abrasive medium between the wafer and the pad and makes the wafer have an excellent planar surface after polishing. The CMP procedure includes a chemical reaction and a mechanical movement, therefore several coefficients such as the down force of the wafer, platen speed, solid content of the chemical slurry, and pH of the chemical slurry etc. significantly influence the efficiency of the polishing.
The conventional CMP does not provide a suitable method for detecting a planar end-point. For example, one conventional method requires a technician to remove a semiconductor wafer from the chemical mechanical polishing process, inspect the wafer for the desired end-point, and then return the wafer to the process if the desired end-point is not observed. This is obviously time-consuming and inefficient. How to control the polishing at an end-point precisely is a major problem in all kinds of wafer polishing.
Several types of end-point detection having no need to remove the semiconductor from the production line have been invented:
1. Motor current method;
2. Pad thermal image;
3. Optic interferometer method;
4. Acoustic method; and
5. Small vibration method.
Although the above-mentioned detecting methods are based on different theories, those methods all need a precise close-loop to assist in controlling the wafer polishing. However, mature controlling techniques of close-loop are not common, so there is a requirement of an excellent controlling technique that can perfectly combine the CMP procedure and the end-point detection on line to increase the quantity of output.
To overcome the existing problem in chemical-mechanical polishing, the present invention tends to provide a method of determining efficient parameters in chemical-mechanical polishing, which achieve high efficiency in the CMP procedure.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying tables and figures.
The main objective of the invention is to provide a method of determining efficiently parameters in chemical-mechanical polishing, especially the parameters of this method involve a time parameter and the parameters are set at the best value.
Another objective of the invention is to provide a method of determining efficiently parameters in chemical-mechanical polishing, whereby the CMP procedure and the end-point detection are efficiently combined on line to increase the quantity of output and diminish the polishing time.
Still another objective of the invention is to provide a method of determining efficiently parameters in chemical-mechanical polishing, wherein the maximum material removal rate (MRR) and the minimum within wafer non-uniformity (WIWNU) are achieved in the CMP procedure.